You can see how the shadow text is displayed first, followed by the
text line, which, though it appears underneath the shadow line in the
HTML code, actually appears slighly above it on the page, because we
use a negative top margin of -64 pixels.

Note: This isn't the best way to overlap text (I'm saving that
for Lesson 5). One reason is that each browser has slightly different
margin defaults, so whereas this drop shadow looks perfect in
Communicator for Mac and IE 4 and 5 for Windows, it doesn't even look
like a drop shadow in other browsers. (If it doesn't in your browser,
play with the margin values until it does.)

(By the way, considering my name, you knew I had to use an X-Files example eventually.)